Electrical distribution system



Oct. 5, 1943. J. s. PARSONS ELECTRICAL DISTRIBU'LLON SYSTEM Filed Aug. 3, 1940 6 Sheets-Sheet 2 h m h WITNESSES:

& RM 0. MP 6 0 M J 06h 1943- J. s. PARSONS 2,331,223

ELECTRICAL DISTRIBUTION SYSTEM Filed Aug. 3, 1940 e Sheets-Sheet s WITNESSES: INVENTOR w John 6. Pa row/7s.

Och 1943. J. s. PARSONS 2,331,223

ELECTRICAL DISTRIBUTION SYSTEM Filed Aug. 3, 1940 6 Sheets-Sheet 4 Fly. 4

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INVENTOR Joli/76. Parsons.

ATT NEY Oct. 5, 1943.

Filed Aug. 3, 1940 6 Sheets-Sheet 6 x a n 3 am TM I n W m M flu WM Wm? Wm? a Q w a Q WITNESSESI INVENTOR John 6". P6019005.

Patented Oct. 5, 1943 ELECTRICAL DISTRIBUTION SYSTEM John S. Parsons, Swissvale, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsyl- Vania Application August 3, 1940, Serial No. 350,385

22 Claims.

This invention relates to electrical distribution systems, and it has particular relation to electrical distribution systems of the network type.

In areas requiring electrical service of good continuity and high density, such as areas occurring in large cities, it has become standard practice to employ distribution systems of the secondary network type. Such a system includes a plurality 'of substantially independent feeder circuits which are coupled to a common secondary network or grid circuit. Each of the feeder cir cuits is coupled to the secondary network circuit through a plurality of network transformers, each provided with a network protector. Under normal conditions of operation, all feeder circuits supply electrical energy to the secondary network circuit.

Should a fault occur on one of the feeder circuits, current flows from the secondary network circuit to the fault through the network transformers and protectors associated with the faulty feeder circuit. Because of the reversal in energy flow, directional relays associated with the protectors trip to disconnect the faulty feeder circuit from the secondary network circuit. Also the feeder circuit breaker associated with the faulty feeder circuit opens under the control of its customary relays to disconnect the faulty feeder circuit from its supply source and remove it from service. The secondary network circuit, however, continues to receive electrical energy over the remaining sound feeder circuits with no interruption of service.

When a fault occurs on the secondary network circuit or grid, the network protectors all remain closed and the fault is burned off. Because of the large currents and electrical energy available from the several feeder circuits, it is entirely practicable to burn off secondary network circuit faults.

Because of the excellent continuity and reliability of service afforded by network distribution circuits, there has been a pronounced trend extending such network circuits to higher voltage fields. For example, network distribution circuits for distributing service at a phase-to-phase voltage of 2300 volts or 4000 volts, are not uncommon. These higher voltages, however, require some modification in the network circuits employed. Network circuits designed for such high voltages commonly are designated as primary network circuits.

Because of the higher voltages which tend to sustain faults and because of the increased damage resulting from a fault occurring on high voltage primary network circuits from a fault of long duration, it is customary to provide such a distribution system with protection not only against feeder circuit faults but against network circuit faults. In a typical primary network system, the feeder circuits are connected to the primary network circuit through network transformers and transformer circuit breakers generally of conventional design. In addition, each network main between adjacent points of connection of the feeder circuits is provided with a pair of sectionalizing switches. These sectionalizing switches have suitable controls for removing faulty network mains from service. Examples of this prior art design may be found in my United States Patents Nos. 1,947,100 and 1,955,311, which are assigned to the Westinghouse Electric & Manufacturing Company.

Although the systems disclosed in my aforesaid patents provide excellent service, their fields of application are restricted because of their cost and complexity. This limitation will be appreciated when it is recalled that each of the network mains requires two sectionalizing switches, together with suitable control equipment.

In accordance with this invention, a simplified primary network distribution system is provided. To this end, a portion of the burden of protecting the system against faults occurring on the network mains is shifted to the transformer cir cuit breakers associated with the network transformers. By this shift, together with suitable revision of the control equipment, it is possible to restrict the sectionalizing switches to one seetionalizing switch for each network main.

According to a specific embodiment of the invention, the transformer circuit breakers are employed substantially in the conventional manner for protecting the system against faults occurring on the feeder circuits. When a fault occurs on one of the feeder circuits supplying the primary network of this invention, the reversal of energy flow through the transformer circuit breakers associated with the faulty feeder operates to trip these breakers. When the feeder circuit breaker associated with the faulty feeder circuit opens, the faulty feeder circuit is completely removed from service.

When a fault occurs on a network main adjacent a. transformer circuit breaker, the excessive current flowing to the fault through the asso ciated transformer trips the breaker. In addi tion, the excessive current flowing through each of the adjacent sectionalizing switches is employed to first trip these sectionalizing switches,

paired. On the other hand, if the fault clears within the closing cycle of the transformer breaker and the breaker remains closed after one of its reclosures, the adjacent sectionalizing switches also close to restore the isolated section of the primary network circuit to its original condition.

For effecting the desired operations, each sectionalizing switch may be provided with overcurrent tripping means, preferably with inverse time delay. In addition, each sectionalizing switch. includes reclosing means effective only when voltage appears on the associated network main on both sides of they sectionalizing section. In many cases it also is desirable to prevent reclosure of the sectionalizing switch when phase conditions across the poles thereof are incorrect.

In a further embodiment of the invention, certain of the sectionalizing switches may be provided with an auxiliary closing control. This auxiliary control is efiective for closingv a sectionalizing switch a restricted number of times when voltage appears on the associated network main on either side of the switch.

It is, therefore, an object of the invention to provide a simplified primary network distribution system.

It is a further object of the invention to provide a primary network distribution system having only one sectionalizing switch in each network main.

It is a still further object of the invention to provide a primary network distribution system wherein a transformer circuit breaker employed .for coupling a feeder circuit to the primary network circuit also is constructed for assisting in the clearance of primary network circuit faults.

It is a further object of the invention to provide a transformer circuit breaker for coupling feeder circuits to a primary network circuit which trips in response to current flowing to a fault occurring on the primary network circuit.

It is a still further object of the invention to provide a transformer circuit breaker for coupling a feeder circuit to a primary network circuit which is designed to reclose a predetermined. number of times after a tripping operation thereof.

It is a further object of the invention to provide a sectionalizing switch for a primary network circuit which recloses only when voltage appears in the associated circuit on both sides of the sectionalizing switch.

It is a further object of the invention to provide a sectionalizing switch for a primary network circuit which recloses only when the phase conditions across its poles are correct.

It is another object of the'invention to provide a primary network comprising a plurality of substantiallyindependent network loop circuits.

It is a still further object of the invention to provide a sectionalizing switch for a primary network system with closing means effective only when'voltage appears in the associated circuit on both sides of the sectionalizing switch and with auxiliary closing means effective for a restricted number of closing operations when voltage appears in the associated circuit on either side of the sectionalizing switch.

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 is a diagrammatic view in single line of a primary network distribution system embodying the invention;

Fig. 2 is a diagrammatic view of a network transformer circuit breaker control system suitable for the system illustrated in Fig. 1;

Fig. 3 is a diagrammatic view of a sectionalizing switch control system suitable for the system illustrated in Fig. 1;

Fig. 4 is a diagrammatic view with parts broken away showing a modification of the network transformer circuit breaker control system illustrated in Fig, 2;

Fig; 5 is a diagrammatic View showing a modification of the sectionalizing switch control systemillustrated in Fig 3;

Fig. 6 is a diagrammatic view showing a modiiied sectionalizing switch control system designed in accordance with the invention; and

Fig. 7 is a diagrammatic single line view showing a modified primary network system embodying the invention.

Referring to the drawings, Fig. 1 shows a primary network system including three feeder circuits l, 2 and 3. Although these feeder circuits may be connected to different sources of energy, for the purpose of illustration they are connected to a common source of energy, such as a bus l through feeder circuit breakers la, 2a and 3a.. The feeder circuit breakers may be of conventional design, including overcurrent relays and ground relays for tripping the circuit breakers upon the occurrence of faults on the associated feeder circuits. Preferably the feeder circuit breakers: are of the reclosing type which reclose for a predetermined number of times after trippingand then look out.

The primary feeder circuits are employed for energizing a common primary network distribution circuit or grid 5-. To this end the feeder circuit I is connected to the network distribution circuit 5 through a plurality of network transformers lb and network transformer circuit breakers lc. Similarly, the feeder-circuits 2 and 3 are connected to the network distribution circuit .5 through network transformers 2b, 3b and through network transformer circuit breakers 2c and 30.

As illustrated in Fig, 1, the network distribution circuit or grid 5 includes a plurality of network mains 6- which are interconnected to form a solid network distribution circuit. For protective purposes, each of the network mains 6 is provided with a sectionalizing switch '5, Eu or lb. These sectionalizing switches all may be of similar construction. However, the reference characters la, and lb are employed for designating certain sectionalizing switches for reasons which will be pointed out below.

Preferably, each sectionalizing switch is positioned substantially at the midpoint of its associated network main. This is for the reason that such a position decreases the duty on the sectionalizing switch. Moreover, somewhat improved regulation is obtained by such a positioning of the sectionalizing switches when a section of the network distribution circuit or grid 5 is out of service.

If desired, however, the sectionalizing switches may be positioned adjacent the network protectors or transformer circuit breakers. This is represented in Fig. 1 by the sectionalizing switch lb which is positioned adjacent one of the network protectors 2c. Such a location for the sectionalizing switch lb has the advantage that the three adjacent units 2b, 2c and lb may be installed at a common point. This is particularly desirable for underground constructions because of the resulting reduction in the number of vaults required for receiving the equipment.

It will be understood that service is derived from any of the network mains. For example, a load may be supplied through a circuit 8 which is connected to one of the network mains through a distribution transformer 9.

The ratings for the system illustrated in Fig. 1 may vary appreciably. For example, the feeder circuits l, 2 and 3 may be three-phase circuits designed to operate at 33 kilovolts, phase to phase. The network transformers lb, 215 and 31) may be designed to reduce the feeder circuit voltage to 4000 volts phase to phase for energizing the network distribution circuit or grid. 5, Generally, the network transformers are tap changing transformers designed for tap changing under load.

Protection for the feeder circuits is afforded by the feeder circuit breakers la, 2a, 3a. and by the network transformer circuit breakers lo, 20 and 30. To this end, the transformer circuit breakers are designed to trip when current exceeding a predetermined magnitude is supplied by the network distribution circuit to a fault occurring on any of the feeder circuits. Preferably, each transformer circuit breaker includes directional tripping means which trips the assosicated breaker substantially instantaneously in response to the reversal of current resulting from the occurrence of a fault on the associated feeder circuit.

Protection for the network distribution circuit or grid 5 is provided not only by the sectionalizing switches I, la and lb, but by the transformer circuit breaker lo, 20 and 30. For this purpose, each of the transformer circuit breakers is provided with overourrent tripping means preferably operating with inverse time delay. Consequently, if a fault should occur on the network distribution circuit 5 at any point, such as the point ll, the nearest transformer circuit breaker to trips after the adjacent sectionalizing switches l, la, and lb have tripped as it is then the only transformer circuit breaker carrying fault current.

The sectionalizing switches I, la and lb are designed to trip in response to overcurrent, pref-- erably with inverse time delay. Consequently, for the fault at the point ll the three nearest sectionalizing switches I, la, trip in advance of more distant sectionalizing switches since they are carrying more fault current. The tripping of the network protector and the three sectionalizing switches completely isolates the faulty section of the network distribution circuit 5 from the remainder of the network distribution circuit. Interruption in service consequently is confined to a small section of the network distribution circuit adjacent the fault II.

For restoring a faulty section to service after clearance of a fault, each of the transformer circuit breakers preferably is provided with automatic reclosing means. This reclosing means may be effective for reclosing each breaker a predetermined number of times, such as three times, after which the breaker is permanently locked out. If the fault at the point ll clears during the reclosing cycle of the associated transformer breaker 3c, the breaker closes and remains closed, thereby energizing the section of the network distribution circuit on which the fault ll occurred.

Each of the sectionalizin switches may be designed to reclose when substantially normal voltage appears on both side thereof. Since the closure of the transformer breaker 30 results in the presence of voltage on both sides of the tripped sectionalizing switches l and la, these sectionalizing switches close to restore the network distribution circuit to its original normal condition.

If the fault fails to clear within the reclosing cycle of the tripped transformer breaker to, the breaker looks out and the three tripped sectionalizing switches l and la fail to close. Consequently, the faulty section remains out of service until the fault is cleared manually and the tripped transformer breaker 3c is manually reset.

A network transformer circuit breaker lc, suitable for the system illustrated in Fig. 1, is shown in detail in Fig. 2. Referring to Fig. 2, the transformer circuit breaker therein illustrated includes a circuit breaker l2 for connecting the network transformer lb to the network distribution circuit '01 grid 5. It should be understood that the invention is applicable to single-phase or polyphase service, and that the ratings may be varied as required by the various installations. For purposes of illustration, however, the network distribution circuit or grid 5 i assumed to be designed for three-phase, four-wire service, having three phase conductors A, B and C and a neutral conductor N.

Energy for operating the circuit breaker i2 is derived from the system through a plurality of current and voltage transformers. Current is ob tained from. three current transformers l3a, l3?) and Lie. Volta e is obtained from the feeder circuit side of the circuit breaker it through three voltage transformer Mo, l ib and lc, which are connected, respectively, between each phase conductor and neutral. Similarly, voltage is obtained from the network distribution circuit or grid side of the circuit breaker l2 through three voltage transformers l5a, I52) and l5c.

For tripping the circuit breaker l2, a tripping solenoid I6 is provided which is energized from a capacitor H. The capacitor l! is charged from the secondary of one of the voltage transformers Ma through a half-wave rectifier l8 of any suitable design. The energizing circuit for the capacitor I! may be traced from one terminal of the voltage transformer I la through a conductor IS, the rectifier iii, a conductor 29, the capacitor H, a conductor 2i and a bus 22 which constitutes a neutral bus for the six voltage transformers. As illustrated in Fig. 2, a neon lamp 23 is connected acros the capacitor ll in series with a resistance 24. The neon lamp may be employed for indicating the presence of voltage across the capacitor IT.

For controlling the operation of the tripping solenoid IS a pair of tripping buses 25 and 26 are provided. The bus 25 is connected to one terminal of the tripping solenoid l6 through a pallet switch 21 carried by the circuit breaker l2. The pallet switch 21 i closed when the circuit breaker is closed. The remaining terminal of the tripping solenoid I6 is connected through a conductor 28 to one terminal of the capacitor H. The remaining terminal of the capacitor 51 is connected to the tripping bus 25. From an inspection of this circuit, it will be observed that any connection between the tripping buses and 26 completes a tripping circuit for the tripping solenoid Hi when the circuit breaker i2 is in closed condition.

If the network transformer lb in Fig. 2 is provided with a star-connected grounded neutral primary winding, no special provision need be provided for protecting the feeder circuit against ground faults. With such a connection of the primary winding, the usual phase relays suffice for ground fault protection. However, for completeness in illustration, the transformer lb is illustrated with a delta-connected primary winding and a star-connected grounded neutral secondary winding.

In order to protect the feeder circuit l against ground faults occuring thereon, a ground relay 29 is connected between one phase conductor of the feeder circuit and ground through a coupling capacitor 38. This ground relay carries a movable contact 3! which normally floats between a pair of back contacts 32 and a pair of front contacts 33. The relay is. designed to close its front contacts when the voltage thereacross increases above a predetermined value, such as 143% of normal voltage. The ,relay is designed to drop and close its back contacts when the voltage thereacross falls below a predetermined voltage, such as of the normal voltage thereacross. accompanied by a small time delay, preferably of the order of second. Conveniently, the relay 29 may be of the electrostatic type. Upon the occurrence of a ground fault on the feeder circuit I, the relay 29 will close either its back contacts or front contacts, depending upon which phase conductor of the feeder circuit is faulted. Closure of the front or back contacts of the relay 29 establishes a connecting circuit between the tripping buses 25 and 26, thereby tripping the circuit breaker l2.

For protection against phase faults occurring on the feeder circuit I, the network protector includes a master relay 34. This master relay includes three phasing windings 35a, 35b and 350, three voltage windings, 36a, 36b and 360, and three current windings 31a, 37b and 310. Each of the current windings is connected for energization from a separate one of the current transformers lad, l3b and I30 in accordance with current passing through one of the phase conductors.

Each of the phasing windings is connected for 1 energization from the voltage transformers in accordance with the voltage across one pair of poles of the circuit breaker it. Each of the voltage windings 36a, 35b and Me is energized in accordance with the voltage'between a separate phase conductor and ground.

When a phase-to-phase or three-phase fault occurs on the feeder circuit I, the master relay $34, is energized for actuating a movable contact 33 into engagement with a pair of tripping contacts 39. The construction of the master relay and its operation are well understood in the art, suitable constructions being illustrated inmy Patents Nos. 1,973,097 and 2,013,836, which are assigned to the Westinghouse Electric & Manufacturing Company.

Generally, it is desirable that the master relay be conditioned for insensitive operation. In other words, the master relay should complete a tripping circuit for the circuit breaker l2 only Operation of the relay 29 preferably is circuit or grid 5.

when current above a predetermined magnitude flows to a fault occurring on the feeder circuit i. Instead of modifying the characteristics of the master relay 34, such insensitive operation may be provided by placing the tripping contacts 39 of the master relay in series with the contacts of three overcurrent relays Mia, iilb and Mic. The energizing windings for these overcurrent relays may be connected in series, respectively, with the current windings 31a, 31b and 310 for energization from the secondaries of the current transformers i311, i-Bb and I30. Each of the relays 40a, 40b and 460 is designed to close its contacts substantially instantaneously when a current in excess of a predetermined value, such as a current corresponding to 300% of normal load current, passes therethrough. Closure of the tripping contacts 39 and the contacts of any one of the relays 48a, 46b and 400 completes a tripping circuit across the tripping buses 25 and 26 for tripping the circuit breaker l2. Such tripping occurs substantially instantaneously or with a delay of the order of of a second.

As above indicated, the circuit breaker l2 should trip when excessive current flows therethrough to a fault occurring on an adjacent section of the network distribution circuit or grid 5. To this end, three overcurrent phase relays lla, am and die have their energizing windings connected in series respectively, with the energizing windings of corresponding relays Ma, 4819 and ite, and corresponding current windings 37a, 31b and 310 for energization from the secondaries of the current transformers I311, |3b and I30. Consequently, these relays 410;, Mb and ile are energized respectively in accordance with the phase currents flowing to a fault occurring in the network distribution circuit or grid 5. Preferably, these relays operate with inverse time delay in a minimum time of approximately 1% seconds when current above a predetermined value, such as3(l0% of normal load current, flows to a fault occurring in the network distribution circuit 5.

For protection against ground faults occurring in the network distribution circuit or grid 5, an additional relay M has its energizing winding connected in the neutral return conductor for the current transformers l3a, I31) and Iiic. This re lay is designed to operate and close its contacts, preferably with an inverse time delay having a minimum delay of the order of 1% seconds, when a ground fault occurs on the network distribution It will be noted that closure of the contacts of any one of the relays Ma, #3117, He or 42, completes a circuit across the tripping buses 25 and 28 and trips the circuit breaker l2.

From the foregoing discussion, it will be apparent that the circuit breaker l2 trips practically instantaneously when a phase-to-phase or three-phase fault occurs on-the feeder circuit I, that the circuit breaker 12 trips with a time delay of the order of /2 second when a ground fault occurs on the feeder circuit i, and that the circuit breaker l2 trips with a time delay of the order of 1%. seconds when a phase or ground fault occurs on the network distribution circuit 5. For closing the circuit breaker ii, a closing motor or solenoid 3 has its energizing winding connected across the output terminals of a rectifier 44. The rectifier maybe of any desired construction, but as illustrated, it consists of a fullwave rectifier employing contact type copper oxide disc rectifiers. One input terminal of the rectifier 44 is connected through a conductor 45 to the neutral bus 22. The remaining terminal of the rectifier is connected through a conductor 46, a variable resistance 41, the contacts of a closing relay 48, a conductor 49, a conductor 50 and the conductor I9 to one terminal of the secondary winding of the voltage transformer Ma. 25 Consequently, when the contacts of the closing relay 48 are closed, the closing solenoid 43 is energized from the voltage transformer I la.

Operation of the closing relay 48 is determined by a drum-type controller and by a setup re- '10 lay 52. Two conditions are required to complete an energizing circuit for the closing relay 48. In the first place, the setup relay 52 must be actuated to its closed position wherein its movable contact 53 partially completes an energizing cirr cuit for the closing relay 48. In the second place, one of the contact bars 54 carried by the drum of the controller 5| must bridge contacts 55.

When these two conditions obtain, an energizing circuit for the closing relay 48 is established which may be traced fromthe neutral bus 22 through back contacts of a pallet switch 56, carried by the circuit breaker I2, a conductor 51, a conductor 58, the energizing winding of the closing relay 48, front contacts 53 of the setup relay 52, the contacts 55, and the conductor |9 to one terminal of the secondary winding of the voltage transformer Ma. It should benoted that the circuit breaker can close only when voltage is present on the feeder circuit. 5 i 3 Operation of the setup relay 52 and of the contact bar 54 both are controlled by operation of the drum controller 5|. To thisend, the drum controller includes a reversible motor 59 which may be of the conventional split-phase type hav-r 5 ing two phase windings 60 and BI. A terminal of each of the phase windings is connected through a common conductor 62 to the neutral bus 22. The remaining terminal of the phase winding 60 is connected through a conductor 63,-; closing contacts 64 on the master relay 34, a conductor 65, back contacts of a pallet switch 66 carried by the circuit breaker l2, and a conductor 61 to one fixed terminal 68 associated with the drum controller 5|. The remaining terminal of the phase winding 6| is connected through a conductor 69, front contacts of a pallet switch 18 carried by the circuit breaker l2, and a conductor H to anotherfixed terminal 12 associated with the drum controller 5|. A continuous cylindrical contact 13 carried by the drum controller determines the connections of the fixed contacts 12 and 68 to one terminal of the secondary winding of the transformer |4a through a fixed contact T4 and the conductor l9.

It will be noted that the fixed contact 12 is connected to the motor 59 through the pallet switch I0 only when the circuit breaker is in closed condition. It will be noted further that the fixed contact 68 is connected to the conductor 63 through the pallet switch 66 and the closing contact 64 only when the circuit breaker I2 is in open condition and the master relay 34 is in closing condition. Depending on which of the fixed contacts 68 or I2 is operatively con- 65 nected to the motor, one of the phase windings 66 or 6| will be connected across the secondary winding of the voltage transformer |4a.

In order to determine the direction of rotation of the motor 59, a reactive impedance 15 is 70 connected between the conductors 63 and 69.

For purpose of illustration, this reactive impedance is illustrated as an inductive reactance.

relay, the conductor 56 and the conductor to one terminal of the econdary winding of the phase winding 60 across the secondary winding of the voltage transformer |4a, the direction of rotation of the motor 59 is such that the drum of the drum controller moves in the direction indicated by the arrow. On the other hand, when the pallet switch 10 closes to connect the phase winding 6| across the secondary winding of the voltage transformer hid, the direction of rotation of the motor 59 reverses to rotate the drum of the drum controller in a direction opposite to that indicated by the arrow.

It will be noted that the cylindrical contact 13 is provided .with two notches l6 and 11. The purpose of these notches is to limit the total movement of the drum controller. Assuming that the drum controller is in its normal condition, as illustrated in Fig. 2, if the motor 59 is energized to actuate the drum of the controller in the direction of the arrow, the maximum movement of the drum is slightly less than one full revolution. This maximum movement is determined by the entry of the fixed contact 63 into the notch H to interrupt the energizing circuit for the motor 59.

If the drum controller has been actuated away from the normal position illustrated in Fig. 2, and the motor 59 consequently is reversed to restore the motor to its initial condition, the drum of the controller will move in a direction oppo- 0 site to the arrow until the fixed terminal 12 reenters the notch 15. Such entry interrupts the energizing'circuit for the motor 59 and brings the drum controller to rest.

Assuming that the parts are in the positions illustrated in Fig. 2, and that the feeder circuit l subsequently is energized, if the phase conditions across the terminals of the circuit breaker l2 are correct the master relay 34 operates to close its closing contacts 64. Such closure completes an energizing circuit for the motor 59 and actuates the drum of the controller in the direction indicated by the arrow.

In response to a predetermined movement of the drum, a contact bar 18 carried by the drum of the controller bridges a pair of fixed contacts l9. Closure of the fixed contacts conipletes an energizing circuit for the setup relay 52 which may be traced from the neutral bus 22, through back contacts on the pallet switch 55, the conductor 51, the energizing windingior the setup elay 52, a conductor 80, the contacts 19 and the conductor I9 to one terminal of the secondary winding of the voltage transformer I la. Complet'ion of this circuit actuates the setup relay 52 and establishes a holding circuit for the relay which may be traced from the neutral bus 22 through the back contacts of the pallet switch 56, the conductor 51, the energizing winding of the setup relay 52, front contacts 8| of the setup gizing circuit for the closing relay 48. This condition is retained until the contact bar 54 bridges the fixed contacts 55. This may occur after the lapse of a predetermined time, such as 5 seconds from theinitiation of movement of the drum controller. As above indicated, the bridging of the contacts 55 completes an energizing circuit for the closing relay 48 and this relay closes its contacts to energize the closing motor or solenoid 43.

The :closure of the circuit breaker 12 opens .the :back contacts of the pallet switch 56 and consequently deenergizestheclosing relay L48 and the setup relayEiZ. These relays thereupon. re.- .turn to .the positions illustrated iniFig. 2.

In addition, closure of the circuit breaker .l2 opens the back contactsof the pallet switch 66 to interrupt the energizing circuit for .the-motoriii and the forward movement of the drum con- .troller, therefore, ceases.

When the circuit .breaker i2 closes, the front contacts of the pallet switch l'il close to establish .a. reversing circuit for the motor :59. The motor .thereuponrotates the ,drum of the controller in a direction opposite to that indicated by the arrow until the fixed contact ":12 again is positioned over the limit notch It. At this time, all

.of the parts in Fig. 2 .are in the positions illus- -.trated,.except that the circuit breaker 12 is closed .andtherelay 29 is in its floating condition. V

The foregoing description'of the operation of thereclosing mechanism for the circuit breaker 1.2 has been based on the assumption that the circuit breaker remains closed atter the initial .energization of its closingsolenoid lt. However,

ifthe fault causing the tripping of the circuit breaker i2 fails to clear before the firstclosure, the circuit breaker trips before the motor 59 .resetsthe drum controller to its initial con- .dition. The operationof the closing mechanism ,under tl iese circumstances now will be setforth.

If the circuit breaker l2 trips after its first reclosure, the closure of the back contacts of the pallet switch 66 restores the energizing circuit for the forward operation of the motor 59. Con- .sequently, the drum of the controller 5| continues rotation in the direction of the arrow without resetting to its normal position. fThe movement of the drum continues until a second contact bar 'la'ia. bridges the fiXed contacts l9. .This second bridging of the fixed contacts "39 again operates to energize the setup relay 52, which partially conditions the actuating coil for the closing relay 58 forlenerg'ization. Continued rotation of the drum brings a contact bar E ia;

into bridging relationship across the fixed contacts 55. This again completes the energizing circuit for the closing relay it and the closing solenoid d3 again is energized to closethe circuit breake 2.

By operation of the pallet switches carried by the circuit breaker, the second .reclosure of the circuit breaker cleenergizes the "setup relay 52 and-the closing relay 48. In addition, the

reversible motor 59 is energized in .a direction.

tact $8. This interrupts the energizing circuit a for the motor 59 and no further forward motion 7 thereof is possible. H

By providing a suitable number of contact bars similar tothe bars E i-and -78, and by -properly spacing these bars, as many reclosures as desired prior to lockout may be obtained. As-an example of a suitable reclosing cycle, the circuit breaker l2 may be 'recloseda-t intervals of 5,1 0

and seconds followed by lockout.-

A design suitable for a sectionalizing switch *1 i .buses 1&5 and let.

is illustrated 'indetail in Fig. 3. This sectionalia ing switch includes. a circuit :breaker ml :for connecting portions-of thenetwork main ".6.

Tripping of the ,circuit breaker BB :is effected by a tripping'solenoidzfl l, "and closure of the circuit breaker is effected by a closing solenoid 82. For operating the circuit breaker era, a pair of voltage transformers 1,83. and 34 have their primaries connected in opendelta across the network main 6 on onesideof:thecircuitbreaker.

.A'second pair of voltage :transformers e5 andtt :have theirprimaries .conne'cted'in .open delta across the network main on the second side of :the circuit breaker.

Energy .for actuating the tripping solenoid ii! is derived from -.a capacitor. '87 which is energized from :the secondary winding of the voltage transformer 6 through a suitable, half-Wave rectifier 88. This energizing circuit may be traced from one terminalof the secondary winding .of the voltage transformer 86 through a conductor &9, the rectifier 83, the condenser :87, a conductor 15M, and :a conductor 82 .to the remaining terminal of :the secondary winding. of the voltage transformer :85. As illustrated in Fig. :3, a :neon tlamp .93 is connected in series with .a resistance 1% across the capacitor '81.

The .neon lamp may be employed for indicating voltage across the condenser 85.

The tripping solenoid :81 is :energied *by the completion .of .a circuit between two tripping Ilhis energizing circuit may be :traced .from one terminal of 'the condenser :83 through front contacts on a pallet "switch i9] carriediby'ithe circuit breakerm the energizing winding for .the' solenoid *B i the tripping bus 96 .andthe :tripping bus 9*5.

Completion of the circuit between the tripping buses is effected by any one of four relays 98, st, l-lliand lfil. Three current transformers 1 6211, H32}? and W620; having their secondaries connected in star, are employed for energizing therelays. fiBy-reference to Fig. 3,, it will'be noted that the relays 98, "99 and we are energized com the transformers in accordance with current passing through thethree phase conductors A, B and C, respectively. The remaining relay l'il i is'con nected inthfe neutral circuit of the 'currenttransformers for .en'ergization in accordance with residual or ground current. Conse- .quently', if a phase-.to-phase, three-phase, or ground fault occurs on the network main 6, at least one of the relays 9.8, =99, tilt and mi will be energized to complete a .tripping circuit between the tripping buses and .95. Preferably, .the relays operate with inverse time delay having a minimum tripping time of approximately 0.6 of a second.

For actuating the closing solenoid of the ;oircuit breaker fill, the energizing winding of the closing solenoid't82:is1connectd .across the output terminals of .arectifier d3. .Ihisrectifier may be of :any desired construction, but for the purpose of illustration, 1a full-wave contact rectifier employing copper .oXide discs .mayibe employed.

The rectifier 113.8,:in'turnpisconnected for energization from.1the1secondar.y winding of the voltage transformer .83 through a circuit which :may be traced from one terminal of the secondary winding through the-conductor 89, a conduc- -tor H14, front contacts EH35 of -a closing relay tilt, an adjustable resistance =|QT,l')h-16Btifi6l H33, a conductor I 518 through the conductor -92 to the 'remai-ning terminal of the-secondarywinding. It

will be noted that closure of the circuit breaker 80 requires actuation of the closing relay I06.

The energizing winding of the closing relay I06 is energized from the secondary winding of the voltage transformer 86 through the conductor 89, a conductor I09, front contacts H of a control relay III, back contacts H2 of an undervoltage relay H3, front contacts H4 of a control rela I I5, the energizing winding of the closing relay I80, a conductor H6, back contacts In of an auxiliary relay H8, the conductor I08 and the conductor 92 back to the secondary winding of the voltage transformer 86. I

It will be noted that energization of the closing relay I06 requires closure of the contacts H0, H2 and H4, which are carried respectively, by the relays III, II 3 and H5. The energizing winding of the control relay III is energized through the back contacts of a pallet switch I28 carried by the circuit breaker 80 from the output terminals H8 I and I of a positive sequence voltage filter IN.

The control relay H5 has its energizing winding connected to the output terminals I22 and I23 of a positive sequence voltage filter I24.

The positive sequence voltage filter I2I is connected for energization from the secondary windings of the voltage transformers 83 and 84 to produce an output dependent upon the positive sequence voltage component present on one portion of the network main 6. quence voltage filter I24 is connected for energization from the voltage transformers 85 and 86 to produce an output dependent on the positive sequence voltage component present on the network main on the opposite side of thecircuit breaker 80. Y

Consequently, the controlled relays I I I and I I5 are energized in accordance with'the positive sequence voltage present on opposite sides of the circuit breaker 80. Each of these relays is designed to pick up and close its front contacts when its energizing voltage is equal to or in excess of avoitage corresponding to approximately 90% of thenorrnal' positive sequence voltage.

The energizing windings of these relays may be required at times to carry approximately 110% of their normal rated voltage continuously.

Preferably, the control relay I I I is a time delay relay having a time delay of the order of 2 or 3 seconds when energized by its normal rated. voltage. This provides a time delay in the closure of the circuit breaker 80 of 2 or 3 seconds. If desired, the control relay I I I may be provided with a similar time delay in its drop out direction as well as in its pickupdirection.

The undervoltage relay H3 has its energizing The positive sequired occasionally to carry 173% of its normal rated voltage.

If the positive sequence voltage present in the network main on each side of the circuit breaker 80 is in excess of 90% of its normal value, and if the phase conditions across the poles of the circuit breaker .80 are correct, the contacts of the relays H3 and I I5 are in closed condition and the front contacts H0 01 the control relay III close at the expiration of two or three seconds to complete an energizing circuit for the closing relay I06. In closing, the closing relay I06 establishes a holding circuit for itself which may be traced from the secondary winding of the voltage transformer 86 through the conductor 92, the conductor I08, the back contacts I H of the auxiliary relay H8, the conductor I I6, the energizing winding of the closing relay I08, front contacts I25 of the closing relay I06, the conductor I04, and the conductor 89 back to the voltage transformer 86. Operation of the closing relay I06 also closes the front contacts I05 to complete an energizing circuit for the closing solenoid 82.

Closure of the circuit breaker 80 completes an energizing circuit for the auxiliary relay I I8. This circuit may be traced from the secondary winding of the voltage transformer 83, through the conductor 92, the conductor I08, a conductor I26, a resistance I2'I, the energizing winding of the auxiliary relay H8, a conductor I29, front contacts of a pallet witch I carried by the circuit breaker 80, a conductor I3I, the front contacts I25 of the closing relay, the conductor I04, and the conductor 89 back to the voltage transformer 86.

Actuation of the auxiliary relay H8 opens the back contacts III to deenergize the closing relay I06. In addition, the auxiliary relay H0 completes a holding circuit for itself which may be traced from the secondary winding of the voltage transformer 86 through the conductor 82, the corn ductor I08, the conductor I26, the resistance HI, the energizing winding of the relay I I8, front contacts I33 of the auxiliary g-elay I I8, the conductor I04, and the conductor 88 back to the voltage transformer 86.

Consequently, the auxiliary relay H8 remains in its actuated position and prevents further opwinding connected for energization in accordance with the vector difference in the outputs of the positive sequence voltage filters I2I and I25.

This relay is designed to pick up and open its back contacts when energized by a voltage in excess of approximately 80% of the normal positive sequence voltage output of the filter. It isv designed to drop out and close its back contacts on a maximum of of the positive sequence voltage output of a filter or as much less than 45% as possible. The purpose of this relay is to prevent closure of the circuit breaker 80 if the phase conditions across the terminals of the-circuit breaker 80 are incorrect. If in repairing the network main 6, two phase conductors are interchanged, or three phase conductors are rotated 120 or 240, the phasing relay will operate to prevent closure of the circuit breaker.

This relay may be reeration of the closing relay I08. This condition continues until the control relay III completely resets to establish a shunt around the energizing winding of the auxiliary relay I I8. This shunt is established by the closing of back contacts i3 0 carried by the control relay I I I. The provision of the auxiliary relay H8 prevents pumping of the circuit breaker 80. For example, if the circuit breaker were to close and promptly trip with the voltage on each side substantially normal, the circuitbreaker would reclose again without substantial time delay were it not for the auxiliary relay I I8. As above indicated, the auxiliary relay H8, under these conditions, would remain in its picked up condition with its back contacts II'I open to prevent energization of the closing relay I06.

The construction of the positive sequence volttage filters may be similar to that illustrated in the Lenehan Patent No. 1,936,797, which is assigned to the Westinghous Electric 81 Manufacturing Company. Each of these voltage filters comprises, in general, an auto-transformer I 35 having a 40% tap I20 or I22. In addition, each filter includes a resistor I36 and a reactor I32. The various elements of each filter are so related that the voltage drop across the resistor I36 is breakers.

rent will flowto the, fault. carrying the "iargestzamount; of thi -fault current equal to the same percentage if the' tdta'l voltage impressed on the resistor I36 and the reactcr lid? :in series as the .ratiopf the autoetransfcrmer ass, :but lag itheztotal vvoltage impressed .on:the resistor and :reactor 160i. .Assumingthatthe phase rotation of ithethree-phaseicircuit isiin ithe order ATE-LC, :each .of ithe .zfilters will have on output proportional to the positive.-sequenceozdltage.component present oniitsportionof/the three.- phasecircult.

From the foregoing description of :the component parts of .the distributi'onrsystem. illustrated in Fig. :1, it is believedthat :the operationcicthe complete system. may .be' set .forth iclearly. :Assuming that theentire system.-is deencrgized,;if

the feeder circuit breakers ta, to and 3a :are

closed, voltage .is impressed on :the control circuits for the transformer circuit breakers .ic, .21: and .30. These breakersclo'se at :the expiration of their initial time delay to energize .iall sections of the network.distributionscircuit:5. .Since voltage is present on both sides :of .each of fthe sectio-nalizing SWitChBs'iT, lo an'd ?b,;and assuming that thepositivesequence voltage. components present on each side ofeachsectionalizing switch are in -eXCess of 190% f :the :normal .value,z*and assuming furtherthatthelphase conditionsiacross the terminals of -each :sectionalizing switch are correct, the sectionalizingswitches .closerat the expiration of their 'twoor three-second tiine delayto interconnect completelythe-networkhistribution circuit. H v I g Should a fault to I ground occur "on one of the phase conductors of a feeder circuit, sush -as "the feeder circuit I, the ground relays 29 associated escapes Depending upon whether'the fault is 'azphaseto phase .rfault, a three-phase fault, or .a phase- .to-ground ifault, :one-or 51110138. or" the .relays 28,599, shill :and 18! :associated withieach of ithe.,section- :alizingiswitchesadjacentthe fault, .willoperate to trip the three';afijacent .sectionalizing :switches. Becausepof :their inverse time delay characteristics, the :adjacent isectionalizing switches will :trip :to removeonly :the. small .faulty section from .the remainder of :the distribution .circuit at :the expiration of ;a uninimumitime of ,;,6 of. av second.

at the expiration {of a minimum time of ,lT o seconds, one or moreioftherrelays glide, dib lic ands? op ra e tot-rip th ne restme -W k t an former circuit .breaker. This completely, isolates the 131113411 faulty section from the remainder of :the .distrihution circuit and'frorn :the feeder circuits a Q-At Tthe qexpiration;of its initial delay in closing, the tripped transformer .circuitbreaker recloses.

If the fault has cleared in the meantime, the

transformer circuit breaker =remains closed, ;but if .the fault is stillpresent, the breaker again trips. If the fault ;is permanent, .the tripped transformer circuit breakengoes .through'its com- .plete reclosing cyclelof 'threareclosures and then .locks .-out. However, if thefault clears before completion of the closingcycle, the trippedtransformer ,circuit breaker remains closed.

With .the transformer circuit breaker locked out,the sectionalizing switches I and ,l'a which have been-tripped, remain in theirgtripped condi- :.tions for the-reason that .voltage'appears ononly one sideof these sectionalizing switches. Under with the transformer circuit breakers ic close normal operation -.of the system consequently:

obtains. If a phase-to phase-cr three-phase fault occurs on one of the feedercircuitsgsuchas the feeder circuit i the master relayfid associated with-each of the transformer circuit-breakers ic' isactuated to :close-its stripping contacts. if :at the same time, the current. flowing .to the:;faul t .isinexeess vof appredeterrnined value,1such as;-3Q0% :ofithe rated load value, one .or more of the instantanecos overcurrent .-relays Ada, 'z liib, doc associated with the transformer circuit breaker 'tciclo-se-ito complete a Ltripping circuit for reach gof .;these Consequently, the :gfeederici'rcuit ii :is again .reinovedxfrom; service until :the fault thereon is cleared. .iIt. isito :be understoodthat'rwheni a faultoccu-rs. onafeedencircuit, the feeder circuit breaker, such as breaker Ia, operates inthe customary. manner to disconnect therfeeder circuit fro-mithezbus 4.

With the distribution system operating normally, if a'faultshould;occunon the:networkdistribution. circuitas; atithevpoint a Lexcessivezcun ilhe-oircuitzhreakers are those associated withvthe nearest iseotional- .ized switches for 1a,;and-the.nearestztransformer rcirouitbreakeric.

these circumstances, theientirernetwork distribution circuit continues to provide serviceexcephfor the srnallfaulty section adjacent the fault =5 i.

,Assurningthat the fault clears ;and that the adjacent transformer ,circuit ,hreaker closes and remains clo se cl thesectionalizing switches fl an 1a -.-whi ch were tripped, ,reclose with a possible timedelayoitwo or threeseconds. .Suchclosure presupposes that the phasaconditions across the 1sectionalizing switches :are correct, and that the .positive phasesequence voltagescmeach side of the sectionalizing switches are .:m excess .of .90

'Withthe closure of the. sectionalizing switches .lihe entire system i ..re- :stored-to normaloperation.

of their-normal .values.

initliig. 2, the controls illustrated for the circuit breaker 1L2 prevent .closure *Of the circuit :breaker .if the phase conditions across the poles thereofiare incorrect. Ifzsuch: protectionagainst incorrect phasing .is unnecessary, the. control circuits for the circuit breaker t? unayzbe simplified appr ciab y. isucha in fig.

simplification is illustrated :Referring .to :Fig. 1.4, it will he nan that :the voltage transformers 5a, 1% and lac .are .omitted. :Moreover, in .placepf :the master .relay -:34 of Fig.2, a simplifiedunasterrelay I38.isshown.

Theimaster relay 2138 is similar to the master relay 331 except for theoinissio-nof :the phasing windings. 'lt willbe :note'dtthat. eachpf \the .voltage windings eflfic, @361) Land 536a .in Fig. :4 is energizedvfrom one of .the-yoltage transformers .I ta, Mhand Me. .The .connectionsiandoperation of the control .circuitsrfor .the .circuit breaker .112 in Fig. 4- otherwise 1-2.1{6 1 5111111 41 .to those shown and described forFig. 2. For-simplicitytin illustration, :Fig. 4 .has .beenrestricted :tothe portion of Fig. awhich has beemmodified. "Sim larly, ithe .control .circuits for the section- 'alizing igswitches :1 may be simplified ibycmitting the phasing control, if phasing is not required. This simplified control is illustrated in Fig. 5.

Referring to Fig. 5, a circuit breaker 80a is illustrated which corresponds to the circuit breaker of Fig. 3. The tripping control circuits for this circuit breaker 80a are similar to those employed in Fig. 3, but have been omitted for clarity in illustration. Two voltage transformers I39 and I40 are connected between the phase conductor A and neutral on opposite sides 01 the circuit breaker 80a. These voltage transformers suflice to energize the control circuits for the circuit breaker 80a. The secondary winding of the transformer I39 is connected through the back contacts of a pallet switch I carried by the circuit breaker 80a to the energizing winding of the control relay III. The secondary winding of the voltage transformer I40 is connected to the energizing winding of a second control relay I43 which corresponds to the control relay I I of Fig. 3.

The control relay III is designed to operate and close its front contacts IIO when the phase A to neutral voltage applied to the transformer I39 is above approximately 90% of its normal rated value. Similarly, the relay I43 is designed to close its front contacts I44 when the phase A to neutral voltage applied to the transformer I40 is above approximately 90% of its normal rated value. Closure of the contacts H0 and I44 completes an energizing circuit for the closing relay I06. This energizing circuit may be traced from one terminal of the voltage transformer I 40 through the contacts I44 and H0, a conductor I45, the energizing winding of the re lay I06, the back contacts II I of the auxiliary relay H8 and a conductor I45, back to the voltage transformer I40. As in Fig. 3, actuation of the closing relay I06 completes a closing circuit for the closing solenoid 02 employed for closing the circuit breaker 80a and also establishes a holding circuit for the relay I06.

As also shown in Fig. 3, closure of the pallet switch I30 which is carried by the circuit breaker 80a, operates to energize the auxiliary relay II8. Actuation of the auxiliary relay IIB deenergizes the closing relay I 06 and prevents further actuation thereof until the control relay III closes its back contacts to shunt the auxiliary relay energizing winding.

If no time delay were provided on the control relay I43, it would be desirable to increase the time delay on the control relay III to approximately one minute to prevent closure of the circuit breaker 80a during the reclosing cycle of a nearby transformer circuit breaker. This is for the reason that certain faults occurring on the side of the circuit breaker 00a which energizes the transformer I40, may not drop the voltage from phase A to neutral appreciably. Consequently, the control relay I I I would remain in its picked up condition and the control relay I43 would close as soon as the associated transformer circuit breaker closes to prematurely close the circuit breaker 80a.

As above indicated, the control relay III may be provided with a long time delay of the order of one minute, to guard against premature closing of the circuit breaker 80a. Preferably, however, both of the control relays III and I43 may be provided with substantially equal time delays of the order of 2 or 3 seconds, and such a construction has been illustrated in Fig. 5.

It should be noted that the relay N5 of Fig. 3 may be given a time delay similar to that of the relay I 43 of Fig. 5. However, this is unnecessary in Fig. 3 for the reason that the relay H5 is energized in accordance with positive sequence voltages. If a fault occurs on the side of the circuit breaker which energizes the voltage transformers and 86, it is unlikely that the positive sequence voltage applied to the relay II5 will be suflicient to actuate the relay.

If phasing is required on neither the transformer circuit breaker nor the sectionalizing switches, the constructions illustrated in Figs. 4 and 5 both may be employed.

Referring again to Fig. 1, it will be noted that under some conditions, the operation of the system is not entirely satisfactory. For example, assume that the feeder circuit I is out of service and that a fault occurs on the distribu tion circuit 5 at the point II. Under these conditions, both of the corner sectionalizing switches Ia will trip since equal fault current flows through both of these sectionalizing switches to the fault. In addition, the sectionalizing switches I adjacent the fault and the transformer circuit breaker 30 adjacent the fault trip to clear completely the faulted section from the remainder of the distribution circuit.

If the fault at the point II clears prior to the completion of the reclosure cycle of the adjacent network protector 3c, the adjacent sectionalizing switches I which tripped, reclose for the reason that voltage appears on both sides thereof. However, the sectionalizing switches 1a remain tripped for the reason that the adjacent transformer circuit breaker I0 is open and voltage cannot appear on this side of the sectionalizing switches Ia. With sectionalizing switches Ia of the construction illustrated in Fig. 3, the corner section normally energized directly from the feeder circuit I would remain out of service despite the fact that the fault had cleared promptly.

In order to permit closure of the sectionalizing switches Ia under the aforesaid circumstances, the design of these switches may be modified as illustrated in Fig. 6.

Referring to Fig. 6, a circuit breaker 001'), which corresponds to the circuit breaker 80a of Fig. 5 is illustrated. The controls for this circuit breaker include control relays Ia and I43a, which correspond to the relays I I I and I43 of Fig. 5. When the voltage from phase A to neutral on each side of the circuit breaker 80b is in excess of of its normal value, the relays Ia and N341 close to complete through their front contacts H0 and I44, an energizing circuit for the closing relay I06. As indicated with reference to Figs. 3 and 5, actuation of the closing relay I06 establishes an energizing circuit for the closing solenoid 82 of the circuit breaker 80b and also establishes a holding circuit for the relay I06. In addition, as also pointed out in connection with Figs. 3 and 5, closure of the pallet switch I30 carried by the circuit breaker 00b, completes an energizing circuit for the auxiliary relay H0. Actuation of the auxiliary relay II8, it will be remembered, deenergizes the closing relay I06 and prevents further energizaticn of the closing relay until deenergization of the auxiliary relay H8.

From the description of Fig. 6 thus far set forth, it will be appreciated that the normal closing operation of the circuit breaker 80b is similar to that of the circuit breaker 80a of Fig. 5. In addition to the closing control circuits thus far described, Fig. 6 discloses an additional closing control circuit which is effective for closing the circuit breaker 8021, even though voltage fails to appear on one side of the circuit breaker.

To permit closure o-fthe circuit breaker 80?) when voltage appears on-either side thereof, a transfer relay I l! has its energizing windingconnected across a secondary of the voltage transformer I48. This transfer'relay'is designed to pickup and close its front contacts 148 when the voltage thereacross is inexcess of about 70% of its normal value. It isv designed to drop and close its back contacts I48 when the voltage falls below about 45% of its normal value. It will be noted that one terminal of each of the transformers I 39 and I48 i connected to a common bus I56. The transfer relay through its front and back contacts I48 and I49, operates to connect a second bus ii! to the remaining terminal of the voltage transformer MI! if the Voltage transformer is properly energized,'or to the remaining terminal of the secondary winding of the voltage transformer I39 if the voltage transformer I I!) is 'deenergized'. Consequently, an operating voltage appears across the buses I58 and II'if a voltage appears, on either side of the circuit breaker 8012.

When the circuit breaker 88b is opened, a pallet switch I52 carried thereby closes its back ccntacts'to connect the energizing winding of a timing relay I53 across the buses I51! and ISL- This connection may be traced from the bus I50 through the pallet switch I52, a conductor I54, the energizing winding of the timing relay I53, the back contacts I55 of a latching relay I55, and a conductor I51 to the bus I5I. quently, the timing relay I53 is energized when the network main on either side of the circuit breaker 86b is energized. I

The timing relay I53 is designed to pick up and close its front contacts I58 when energized by a voltage in excess of approximately 90% of normal voltage with a substantial time delay, such as 12 or' 13 seconds. This time delay is such that the control relays IIIa and H311 will operate first to close the circuit breaker 8% if adequate,

voltage is present in the network main-on both sides of the circuit breaker.

If voltage ispresent in the network main on onlyone side of the circuit breaker, the circuit breaker remains open until the expiration of the time delay of the timing relay I53. At the expiration of thi time delay, the timing relay operates to close its front contacts I58. This establishes an energizing circuit 'for the closing relay Hi5, which may be traced from the bus Iiil 7 through the contacts IE8, the energizing winding of the closing relay I BE, and the back contacts Ii! of the auxiliary relay H8 to the bus I59. Consequently, the closing relay operates to close the circuit breaker 80b in the customary manner. Closure of the closing relay I06 also operates to energize the auxiliary relay I I8 as above pointed out, to interrupt the energizing circuit for the closing relay'and to prevent further energization thereof until the auxiliary relay I I8 resets.

' Since the absence of voltage on one side of the sectionalizing. switch may be the result of a fault, it is desirable to prevent repeated operations of the timing relay I53. To thisend, front contacts I59 are provided on the'timing relay for energizing the latching relay I56. This energizing circuit may be traced from the bus I5I, through the conductor I51, a: conductor I69, the front contacts I59, the energizin windin of the latching relay I56, back contacts IIiI carried by- Consethe latching relay'anda conductor I 62 to the bus I50. Actuation of the latching relay opensthe energizin circuit for the timing relay I53. Actuation of the-latching relay I56 also results in the engagement of a latching pin I63 with'a latching lo I M carried by the latching relay. The latching pin IE3 is carried by the armature of a solenoid I65 and is biased into latching position by means of a spring I66.

From an inspection of 'Fig. 6,-it will be noted that after one actuation of the timing relay I53, the latching relay I56, is latched to prevent further actuation of the timin relay. Consequently, if a fault is present in the network main on one side of the circuit breaker 821b, the timing relay I53 will produceone closure of the circuit breaker 8th and thereafter the circuit breaker will remain open.

If desired, the latching relay I56 may be reset manually by manually withdrawing the pin I63 from engagement with the lug I54. For completeness, however, an automatic unlatching circuit is illustrated in Fig. 6.

It will be observed that the armature of a solenoid IE5 is associated with-the latching pin IE3. Energization of the solenoid I65 is controlled by front contacts I61 and I68 carried respectively, by the control relays IIIaand I43a.

Assuming that the latching relay I56 is in latching condition, a normal operation of the control relays I I Ia and I43: operates to unlatch the latching relay I56. When both of the control relays II Ia and I43a'are actuated, the closure of the front contacts I67 and 58 completes an energizing circuit for the solenoidIE5 which may be traced from the bus I5I through a conductor I59, the front contacts I58 and I51, a conductor Iii), the energizing winding of the solenoid I55 and the conductor 2 to the bus I58. Energizetion of the solenoid I65 withdraws the latching pin IE3 from engagement with the lug I64 and permits the latching relay I55 to drop to the position illustrated in Fig. 6.

Since under certain conditions, the control relay II la may be connected to thenetwork main on the deenergized side of the circuit breaker 801), it follows that the back contacts I34 of this relay would not open to permit energization of the energizing winding of the auxiliary relay I I8.

With this modification actuation of either of the relays II Ia or I53 sufiices to permit energization of the auxiliary relay I I8.

Although Fig. 6 illustrates the modification as applied to the closing control circuit of Fig. 5, it should be noted that the same modification may be employed with the control circuits of Fig. 3 if a phasing control is desired. The tripping circuit for the circuit breaker 8% may be similar to that illustrated in Fig. 3 for the circuit breaker 89.

Referring again to Fig. 1, assuming that the feeder circuit I is deenergized, and assuming further that a temporary fault occurs at the point II, if the corner sectionalizing switches 7a are of the type disclosed in Fig. 6, these sectionalizing switches will reclose after clearance of the fault, despite the absence of, voltage on the side of the switches la adjacent the transformer circuit breaker Ic.

Fig. '7 illustrates a modified distribution system wherein the network distribution circuits take the form of substantially independent loops. The advantages obtained from the loop construction are set forth in my copending applications Serial Nos. 342,938, and'342,940, filed June 28, 1940, and assigned to the Westinghouse Electric & Manufacturing Company. When employing the loop circuit type of network distribution circuit, it is desirable that all of the sectionalizing switches be similar to the sectionalizing switch 1a illustrated in Fig. 6. Aside from the loop form of network distribution circuit, and the construction of the switches 1a, the system illustrated in Fig. 7 is similar to that of Fig. 1.

Although the invention has been described with reference to certain specific embodiments thereof, numerous modifications are possible. Therefore, the invention is to be restricted only by the appended claims when interpreted in view of the prior art.

I claim as my invention:

1. In an electrical distribution system, a plurality of feeder circuits, a common distribution circuit interconnecting said feeder circuits for receiving energy therefrom, means responsive to current passing through a section of said distribution circuit associated with one of said feeder circuits for isolating said section from the remainder of said distribution circuit, means responsive to the condition of said one feeder circuit and said section when a fault occurs thereon for isolating said one feeder circuit from said section, means for restoring the connection of said one feeder circuit to said section, and means effective only when substantially normal voltage is present on said section for reconnecting said section to the remainder of said distribution circuit.

2. In electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to the condition of the associated one of said feeder circuits when a fault occurs thereon for interrupting the coupling of said one feeder circuit to said network distribution system, a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having only one of said sectionalizing switches therebetween, and means responsive to current flowing through each of said sectionalizing switches for tripping the associated sectionaiizing switch.

3. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to current flowing therethrough to a, fault occurring on said system for interrupting the coupling of the associated one of said feeder circuits to said network distribution system, a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having only one of said sectionalizing switches therebetween, and means responsive to current flowing through each of said sectionalizing switches for tripping the associated sectionalizing switch.

4. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive independently to the magnitude of current and to the direction of power flowing through the associated one of said feeder circuits for interrupting the coupling of said one feeder circuit to said network distribution system, a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuit to said network distribution circuit having only one of said sectionalizing switches therebetween, and means responsive to current flowing through each of said sectionalizing switches for tripping the associated sectionalizing switch.

5. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to the condition of the associated one of said feeder circuits when a fault occurs thereon for interrupting the coupling of said one feeder circuit to said network distribution system, a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having one of said sectionalizing switches therebetween, each of said sectionalizing switches comprising tripping means responsiv to the magnitude of current flowing therethrough.

6. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical ener y to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to the condition of the associated one of said feeder circuits when a fault occurs thereon for interrupting the couplingof said one feeder circuit to said net work distribution system, and a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of saidfeeder circuits to said network distribution circuit having one of said sectionalizing switches therebetween, each of said sectionalizing switches including closing means operable only in the presence of voltage on both sides thereof.

7. In an electrical distribution system, a network'distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said trans ormer meansfor controlling the coup-ling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to-the condition of the associated one of'said feeder circuits when a fault occurs thereon for interrupting the coupling of said one feeder circuit to said netcircuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer meansfor controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to the condition of the associated one of said feeder circuits when a fault occurs thereon for interrupting the coupling of said one feeder circuit to said networkdistribution system, and a pluralityof sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having one of said sectionalizing switches therebetween, each of said sectionalizing switches comprising tripping means responsive with inverse time delay to the magnitude of current flowing therethrough, and closing means for each of said sectionalizing switches, each. of said closing means being effective for closing the associated sectionalizing switch only when voltage is present on the associated main on both sides of said sectionalizing switch.

9. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits sectionalizing switches positioned in-said network mains between points of connection thereof for sectionalizing said network mains, and closing means for each of said sectionalizing switches, .each of said closing means being effective only when the phase conditions across the poles of the associated sectionalizing switch are correct.

10. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, a plurality of sectionalizing switches positioned in said network mains between points of connection thereof for sectionalizing said network mains, first closing means for said protective means, and second closing means for said sectionalizing switches, the second closing means of the sectionalizing switches adjacent an open protective means being effective only after closure of said open protective means. 11. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, tripping means for said protective means, said tripping means including means responsive with relatively little time delay to the direction of current flow through the associated protective means and said tripping means including means responsive 'with substantial time delay to the magnitude of current flow through the associated protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, tripping means for said protective means, said tripping means including means responsive with relatively little time delay to the direction of current flow through the associated protective means and said tripping means including means responsive with substantial time delay to the magnitude of current flow through the associated protective means for tripping said protective means, and sectionalizing means for sectionalizing said network mains between points of connection thereto of said feeder circuits, each of said sectionalizing means comprising current responsive tripping means, and closing means operable only when substantial voltage is present in the associated means for coupling each of said feeder circuits to each of said loop circuits at a plurality of points, the points of connection of said feeder circuits to each of said loop circuits alternating uniformly around said loop circuits, current responsive means for interrupting the coupling of each of said feeder circuits to said loop circuits, sectionalizing means between each adjacent pair of said points of connection for sectionalizing said loop circuits, means responsive to current flowing through each of said sectionalizing means for tripping the associated sectionalizing means, and means for closing each one of said sectionalizing means effective only when substantial voltage appears on both sides of said one of said sectionalizing switches, said loop circuits being electrically connected to each other only through said feeder circuits.

14. In a polyphase electrical distribution system having a first polyphase portion and a second polyphase portion, a sectionalizing switch for coupling said portions, means for tripping said switch, means for closing said switch, and means for controlling said closing means comprising means for deriving from said first portion a first quantity dependent on a phase sequence voltage component of the energization thereof, means for deriving from said second portion a second quantity dependent on a voltage component of the energization thereof of the same phase sequence as said first-named component, and control means effective for permitting operation of said closing means only when said first quantity, said second quantity and a resultant of said first and second quantities all are within predetermined ranges.

15. In an electrical distribution system, means for sectionalizing portions of said system including a sectionalizing switch, means for tripping said sectionalizing switch, means for closing said sectionalizing switch, said closing means being effective for a closing operation only when substantial voltage is present in said system on both sides of said sectionalizing switch, means for conditioning said closing means for operation when a voltage is present in said system on either side of said sectionalizing switch, and means restricting said conditioning means to only a restricted number of immediately consecutiv operations of said closing means.

16. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to the condition of the associated one of said feeder circuits when a fault occurs thereon for interrupting the coupling of said one feeder circuit to said network distribution system, and a plurality of sectionalizing switches for sectionalizing said network mains, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having one of said sectionalizing switches therebetween, each of said sectionalizing switches including closing means operable only in the presence of voltage on both sides thereof, certain of said sectionalizing switches also including means conditioning the associated closing means for a restricted number of immediately consecutive operations in response to the presence of voltage on either side of said certain of said sectionalizing switches.

17. In a polyphase electrical distribution system having a first polyphase portion and a second polyphase portion, a sectionalizing switch for coupling said portions, means for tripping said switch, means for closing said switch, and means for controlling said closing means comprising means for deriving from said first portion a first quantity dependent on the positive phase sequence voltage component of the energization thereof, means for deriving from said second portion a second quantity dependent on the positive phase sequence voltage component of the energization thereof, control means effective for permitting operation of said closing means only when said first quantity and said second quantity are above predetermined values, and means responsive to the vector difference between said quantities for preventing operation of said closing means.

18. In an electrical distribution system, means for sectionalizing portions of said system including a sectionalizing switch, means for tripping said sectionalizing switch, means for closing said sectionalizing switch, and control means for controlling the operation of said closing means, said control means including first means effective only when substantial voltage i present in said system on both sides of said sectionalizing switch for operating said closing means, and second means effective when voltage is present in said system on one side of said sectionalizing switch for operating said closing means, one of said first and second means being designed to control said closing only if the other of said first and second means fails to initiate a closure of said sectionalizing switch within a predetermined time.

19. In an electrical distribution system, means for sectionalizing portions of said system including a sectionalizing switch, means for tripping said sectionalizing switch, means for closing said sectionalizing switch, and control means for controlling the operation of said closing means, said control means including first means effective only when substantial voltage is present in said system on both sides of said sectionalizing switch for operating said closing means, second means effective when voltage is present in said system on either side of said sectionalizing switch for operating said closing means, said second means having a delay in operation sufiicient to permit prior operation of said first means if voltage is present in said system on both sides of said sectionalizing switch, and lock-out means for rendering said second means inoperative after a predetermined operation thereof.

20. In an electrical distribution system, means for sectionalizing portions of said system including a sectionalizing switch, mean for tripping said sectionalizing switch, means for closing said sectionalizing switch, and control means for controlling the operation of said closing means, said control means including first means effective only when substantial voltage is present in said system on both sides of said sectionalizing switch for operating said closing means, second means effective when voltage is present in said system on either side of said sectionaliaing switeh ror operating said closing means, said second in ans having a delay in operation suflicient tofp' ii'iit prior operation of said first means if voltage is present in said system on both sides of said sectionalizing switch, lock-out means for rendering said second means inoperative after a predetermined operation thereof, and means responsive to the presence or voltage in said system on both sides of said sectionalizing switch for restoring said second means for further operation following an operation of said lock-out means. r

21. In an electrical distribution system, a network distribution circuit having a plurality of connected network mains, a plurality of feeder circuits for supplying electrical energy to said network distribution circuit, a plurality of transformer means for coupling said feeder circuits to said network distribution circuit, protective means associated with each of said transformer means for controlling the coupling of said feeder circuits to said network distribution circuit through said transformer means, each of said protective means being responsive to current flowing therethrough for interrupting the ecu pling of "said one feeder circuit to said network distribution system, and a plurality of current responsive sectionalizing switches for sectional- 'izing said network mains, each adjacent pair of coupling points of said feeder circuits t'q said network distribution circuit having one of said sectionalizing switches therebetween, each of's'aid s'ectidnal'iz'ing switches including closing means operable only in the presence of voltage on both sides thereof.

22. In an electrical distribution system, a network distribution circuit having a plurality or connected network mams a plurality of feeder circuits for sup'i lyihg electrical energy to Said network distr-ibutionciicuit, a pltiiality or transforiiiez means io'r ceupling 'said'feeder circuits to said network distribution oii'c'uit, protective means associates with ea nor said trans ormer means for controlling :tne coupung or said feeder circuits 'to Said network distribution circuit through "said transformer means; each or Said protective means being responsive to current flowing thr'ethrb'ug-h for inte'rrupt'ing the coupling of said one feeder circuit to said network distribution system, and a plurality of cur-rent responsive s'e'ctionaiizing switches for sectional-i2- ing said networkmain-s, each adjacent pair of coupling points of said feeder circuits to said network distribution circuit having one of said seetionauzm-g switches tnereeetween, each of Said s e'ctior ialiaing switches mending cm fig means, first means effective for operating said closing means only when substantial voltage is present in 'said system on both sides of the associated sectional ini g switch, and second means effective for operating said closing means when volt-age is present in said system on either side o'f't-he "asscented sect-manning fSWl CCh, said second means bein' diaerabre y atter a delay sit-meant to ermit prior 'ope ati'on or said 'i f voltag is present in "said system on both side or "saidsectiomunn switm JOHN "S. PARSONS- 

